Preheat the oven to 325 degrees. Place butter in mixer and beat with paddle until soft and light. Beat in sugar in a stream and continue beating 5 to 10 minutes until the mixture is very light and whitened. Stir in the flour by hand until it absorbed, no more or the dough will toughen.
Scrape the dough onto a floured surface and flour the dough with pinches of flour. Press the dough out with your hands, then roll over once or twice very gently with a rolling pin until the dough is about 1/2-inch thick. Cut the dough with floured cutters and transfer the cut pieces to a paper lined pan.
Bake the shortbread for about 15 minutes until it is very lightly colored. Cool the shortbread on a rack.
To use a shortbread mold to shape, press the mold into the floured dough and cut around it. Transfer the cut and molded dough to a paper lined pan and chill about 1 hour until firm. Bake as above.